This invention relates to an air pulser for blasting pulse air, and a powder transporting nozzle, a powder supply device, an air knocker and a bridge breaker using the air pulser.
Heretofore, it is ordinarily done to carry powder and granular material by air or destroy bridges of powder and granular material filled in a hopper by intermittently blasted compressed air or so-called pulse air.
For example, in a transporting device for powder and granular material described in JP patent publication 5-330652, a compressed air supply source comprising a compressor and a pressurized tank are brought into communication with each other through a first passage, and a transporting pipe for powder and granular material connected to a lower outlet of the pressurized tank and the compressed air supply source are brought into communication with each other through a second passage. An electromagnetic valve is connected to each of the first and second passages to control the opening and closing of the respective electromagnetic valves to alternately supply pulse air into the pressurized tank and the transporting pipe, thereby fluidizing the powder and granular material by pulse air supplied into the pressurized tank to suppress the formation of bridges. Also, by pulse air supplied into the transporting pipe, the powder and granular material discharged from the pressurizing tank into the transporting pipe is air-carried.
Also, in the air vibrator described in JP patent publication 6-30735, a valve chamber is provided above a cylinder, a diaphragm having a small hole is stretched in the valve chamber to partition the valve chamber into an upper chamber and a lower chamber into which compressed air is supplied, and an electromagnetic valve is connected to an air exhaust port formed in the peripheral wall of the upper chamber. Opening and closing of the electromagnetic valve is controlled to exhaust compressed air in the upper chamber by opening the electromagnetic valve, and open the top end of the cylinder by deflecting the diaphragm toward the upper chamber as the pressure in the upper chamber lowers, thereby lowering a piston mounted in the cylinder by pulse air supplied from the lower chamber into the cylinder to strike a striking plate with the piston.
In such a powder transporting device or an air vibrator, there are problems that an electromagnetic valve is required to form pulse air. Thus the device tends to be large, and the cost is high since it is necessary to control the opening and closing of the electromagnetic valve with a control device.
An object of this invention is to provide an air pulser which can blast pulse air only by continuously supplying compressed air without using an electromagnetic valve. Another object is to provide a powder transporting nozzle and a powder supply device which use the air pulser, and an air knocker and a bridge breaker capable of intermittently imparting striking force.
According to this invention, there is provided an air pulser comprising a body having an inner space, a diaphragm having a small hole and stretched in the inner space of the body to partition the inner space into an air supply chamber and an air exhaust chamber, the diaphragm being imparted with an elastic force so as to be normally deformed toward the air supply chamber, an air blast cylinder provided in the air supply chamber and closed by the diaphragm and communicating with the air supply chamber when in its open state, a valve plate provided in the air exhaust chamber to partition the air exhaust chamber into a first chamber and a second chamber, the valve plate being formed with a valve hole, a valve body provided in the second chamber to control the opening of the valve hole, and a permanent magnet provided in the second chamber to support the valve body so as to be movable relative to the valve plate and hold the valve body in a closed state by attracting the valve plate to the valve body by a magnetic force, the body being formed with an air supply port for supplying compressed air into the air supply chamber and an air exhaust port for exhausting air in the second chamber to outside.
In the air pulser having such a structure, when compressed air is supplied into the air supply chamber through the air supply port, it flows through the small hole formed in the diaphragm into the first chamber of the air exhaust chamber. When the pressure in the first chamber overcomes the attracting force of the permanent magnet, the valve body retreats to open the valve hole, so that compressed air in the first chamber flows through the valve hole into the second chamber and is discharged to outside. The pressure in the air exhaust chamber will drop below the pressure in the air supply chamber, so that the diaphragm is deformed toward the air exhaust chamber, thus opening the air inlet of the air blast cylinder. Thus, compressed air in the air supply chamber flows into the air blast cylinder and is blasted therefrom.
Also, when the pressure in the air exhaust chamber is kept substantially at the atmospheric pressure, the attracting force acting between the permanent magnet and the valve plate returns the valve body to a state in which it closes the valve hole. After the valve body has been closed, the diaphragm is deformed toward the air supply chamber to close the air inlet of the air blast cylinder and shut off flow of compressed air from the air supply chamber to the air blast cylinder.
The valve body opens every time the pressure in the first chamber increases. Every time the valve body opens, the diaphragm is deformed toward the air exhaust chamber to open the air inlet of the air blast cylinder. Thus it is possible to intermittently blast pulse air.
The powder transporting nozzle according to this invention comprises a nozzle body formed with a suction passage and a discharge passage communicating with the suction passage, and an air pulse generating unit for blasting pulse air toward the discharge passage. The air pulse generating unit has the same structure as the air pulser according to the present invention. The air blast cylinder is arranged to oppose the air inlet end of the discharge passage.
With this arrangement, pulse air is intermittently blasted into the discharge passage from the air pulse generating unit, and every time air is blasted, a negative pressure is produced in the suction passage.
Thus, by connecting a hose to an end of the suction passage and inserting the tip of the hose into powder and granular material in the open-topped container, it is possible to suck up powder and granular material in the container into the suction passage and discharge it through the discharge passage.
The powder supply device according to this invention comprises a diffuser for discharging powder and granular material, an air pulser for blasting pulse air toward the inlet of the diffuser, and a hopper for storing powder and granular material. The hopper has its outlet at its bottom protruding into a mixing space formed between the air pulser and the diffuser. The air pulser has the same structure as the air pulser of the first invention. The air pulser has its air blast cylinder arranged so as to oppose the material inlet of the diffuser.
With this arrangement, pulse air is intermittently blasted from the air pulser into the diffuser, and every time air is blasted, it is possible to feed powder and granular material from the hopper into the diffuser, and intermittently discharge powder and granular material through the diffuser.
The air knocker according to this invention comprises a cylinder, a piston and a return spring mounted in the cylinder, the return spring biasing the piston in a direction away from a striking plate mounted to the tip of a cylinder. An air pulser for blasting pulse air into the cylinder is provided at the rear end of the cylinder. The air pulser has the same structure as the air pulser according to the first invention. The air pulser has its air blast cylinder integral with one end of the cylinder.
With this arrangement, since pulse air is intermittently blasted into the cylinder from the air pulser, every time air is blasted, it is possible to advance the piston and intermittently strike the striking plate with the piston.
Thus, by mounting the striking plate to the hopper, it is possible to intermittently impart vibrations to the hopper. Thus it is possible to suppress formation of bridges in powder and granular material filling the hopper. Also, if bridges should be formed, it is possible to destroy the bridges.
The bridge breaker according to the present invention comprises a storage tank, an air nozzle mounted so as to extend through a peripheral wall of the storage tank for storing powder and granular material, an umbrella-like elastic member mounted to a tip of the air nozzle disposed in the storage tank and having its outer peripheral edge in elastic contact with the inner surface of the storage tank to form a space inside the elastic member. The air nozzle is formed with an air passage communicating with the space, and an air pulser connected to the rear end of the air nozzle for blasting pulse air into the air passage. The air pulser has the same structure as the air nozzle according to the first invention. The air nozzle is connected to the air blast cylinder of the air pulser.
With this arrangement, pulse air is intermittently blasted from the air pulser into the air nozzle, and through the nozzle into a space formed between the elastic member and the inner surface of the storage tank. Every time air is blasted, the pressure in the space rises so that the elastic member is elastically deformed in such a way as to be flattened. Due to such deformation, a gap is formed between the elastic member and the inner surface of the peripheral wall of the storage tank, so that air in the space is blasted through the gap into the storage tank. Thus, the powder and granular material filling the storage tank fluidizes, so that if bridges are formed, they are destroyed.
The bridge breaker according to this invention comprises a storage tank, an elastically deformable elastic sheet provided on the inner surface of the storage tank to form a sealed gap inside of the elastic sheet, and an air pulser connected to the rear end of a nozzle cylinder extending through the storage tank and having its tip positioned in the sealed gap for blasting pulse air into the nozzle cylinder. The air pulser has the same structure as the air pulser according to the first invention. The nozzle cylinder is connected to the air blast cylinder of the air pulser.
With this arrangement, when pulse air is intermittently blasted into the nozzle cylinder from the air pulser, the pulse air is fed into the sealed space, so that the elastic sheet inflates in the storage tank, thereby pressing the powder and granular material filling the storage tank. Thus, if bridges are formed, they will be destroyed.